Sheath width effect on the determination of plasma frequency in the cutoff probe

Kim, D. W.; You, S. J.; Kim, J. H.; Chang, Hong‐Young; Oh, Wang‐Yuhl

doi:10.1063/1.4729442

Cited by 18 publications

(9 citation statements)

References 11 publications

(14 reference statements)

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“…When we see the phase of transmission spectrum (strictly speaking phase difference spectrum between current and voltage), the sign of the phase changes with frequency in series, plus, minus and plus [7,10]. This sign changes are originated from the fact that the property of the cutoff probe changes with frequency in series, capacitor, inductor, and capacitor as noted in the previous studies [7,9,10]. Figure 2 shows the phase of transmission spectrum obtained from the FDTD simulation at the condition of n e = 2.5 × 10 10 cm −3 , p = 6.7 Pa, S = 0.33 mm, and T e = 2 eV (see black line).…”

Section: Resultsmentioning

confidence: 72%

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Computational study on reliability of sheath width measurement by the cutoff probe in low pressure plasmas

et al. 2015

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Recently, the technique for measurement of the sheath width by using the cutoff probe and its equivalent circuit model was proposed and conducted experimentally. In this study, we investigate the reliability of this technique based on the computational simulation. The simulation of three-dimensional Finite-Difference Time-Domain reproduces the transmission spectrum of the cutoff probe with an input parameter of sheath width. We measure the sheath width by using the circuit model and calculate the discrepancy between them under various input plasma densities and sheath widths. The results show the acceptable discrepancy under all of the conditions we studied (the largest discrepancy is about 45%). This indicates that the technique for measurement of sheath width around the floating tip of cutoff probe is robust and reliable.A shorter version of this contribution is due to be published in PoS at: 1 st EPS conference on Plasma Diagnostics

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Section: Resultsmentioning

confidence: 72%

“…Recently, for improving the cutoff probe, the effect of sheath width on the measured plasma density from cutoff probe has been investigated [9,10]. Kim et al [10] presented the technique for measurement of the sheath width by using the cutoff probe and its equivalent circuit model.…”

Section: Introductionmentioning

confidence: 99%

Computational study on reliability of sheath width measurement by the cutoff probe in low pressure plasmas

et al. 2015

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“…However, as the pressure increases above 500 mTorr, the minimum peak broadens and the shape of the S 21 spectra appears to be similar to that of the vacuum S 21 of BCP as shown in figure 2(d). This result is because the wave cut-off phenomenon does not properly occur when the electron-neutral collision frequency is near or higher than the driving frequency [1,46]. Thus, the measurable pressure range of BCP is approximately up to a few Torr when we use S 21 spectra to obtain the cutoff frequency, but this pressure limitation can be solved if the phase-resolved cut-off method is used [42,43].…”

Section: Resultsmentioning

confidence: 98%

Flat cutoff probe for real-time electron density measurement in industrial plasma processing

Yeom

Kim

Choi

et al. 2020

Plasma Sources Sci. Technol.

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The microwave cutoff probe (CP) is an accurate diagnostic technique to measure absolute electron density even in processing gas plasmas. Because this technique needs the installation of two probe tips and a probe body in the plasma chamber, it may cause plasma perturbation in semiconductor plasma processing; this may increase the uncertainty of the measured value. In this work, a flat CP, which is embedded in the substrate chuck or chamber wall, is proposed to measure electron density without plasma perturbation and to monitor processing plasma in real-time. We first evaluated the performance of various types of flat CPs, such as the point CP, ring CP, and bar cutoff probe (BCP), through electromagnetic (EM) field simulation. The BCP showed better performance with clearer cut-off signal characteristics and minimization of noise signals compared with the other probe types. Therefore, we focused on the characteristics of the BCP through experiments and/or EM simulations and concluded the followings: (i) the measured electron densities of the BCP agree well with those of the conventional CP; (ii) the BCP measures the plasma density near the plasma-sheath boundary layer, which is very closely adjacent to the chamber wall or wafer; (iii) it was demonstrated for the first time that the plasma density can be measured, even though the processing wafers such as un-doped silicon, P type silicon, amorphous carbon, or amorphous carbon/SiO2 patterned wafers were placed on the flat CP; and (iv) we performed real-time measurements of the electron density using the BCP covered with the wafers in plasmas with various process gases, such as Ar, NF3, and O2. These results indicate that the chuck-embed-type or wall-type flat CP can be used as a real-time electron density measurement (monitoring) tool during industrial plasma processing, such as during etching, deposition, sputtering or implantation, and the chuck-embed-type flat CP can measure the plasma density impinging on the wafer in real-time without stopping the processing.

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“…For comparison, Figure 7 also shows the full-wave simulated results obtained thru CST [11]. Simulations are performed based on the Drude model in Equation ( 3), which is a popular model that describes its interaction between plasma and electromagnetic waves [8,9,12,15,16]. For comparison, Figure 7 also shows the full-wave simulated results obtained thru CST [11].…”

Section: Experimental Results and Analysismentioning

confidence: 99%

Plasma Generator with Dielectric Rim and FSS Electrode for Enhanced RCS Reduction Effect

Cho

Ahn

et al. 2021

Sensors

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In this study, a method was experimentally verified for further reducing the radar cross-section (RCS) of a two-dimensional planar target by using a dielectric rim in a dielectric barrier discharge (DBD) plasma generator using a frequency selective surface (FSS) as an electrode. By designing the frequency selective surface such that the passbands of the radar signal match, it is possible to minimize the effect of the conductor electrode, in order to maximize the RCS reduction effect due to the plasma. By designing the FSS to be independent of the polarization, the effect of RCS reduction can be insensitive to the polarization of the incoming wave. Furthermore, by introducing a dielectric rim between the FSS electrode and the target, an additional RCS reduction effect is achieved. By fabricating the proposed plasma generator, an RCS reduction effect of up to 6.4 dB in X-band was experimentally verified.

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Sheath width effect on the determination of plasma frequency in the cutoff probe

Cited by 18 publications

References 11 publications

Computational study on reliability of sheath width measurement by the cutoff probe in low pressure plasmas

Computational study on reliability of sheath width measurement by the cutoff probe in low pressure plasmas

Flat cutoff probe for real-time electron density measurement in industrial plasma processing

Plasma Generator with Dielectric Rim and FSS Electrode for Enhanced RCS Reduction Effect

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